The entry of alanine into the gluconeogenic pathway and the regulation of the direction of metabolite flow by enzyme activity will be studied under experimental conditions which may be applicable to human metabolism. Experiments will be carried out with a number of animals species including swine, which may be the best model for man. This will be accomplished by a study of the varied distribution patterns of the alanine aminotransferase and phosphoenolypyruvate carboxykinase isoenzymes in the gluconeogenic tissues from a number of species. Glucose production from alanine in a variety of tissue preparations, including hepatocytes, will be correlated with the level of mitochondrial alanine aminotransferase in order to show its participation in the alanine entry pathway. Isolated mitochondria will be used to study the conversion of alanine to dicarboxylic acids. This investigation will also include a study of the correlation of cytosolic alanine aminotransferase and phosphoenolypyruvate carboxykinase activities, how they are regulated and how they contribute to the direction of metabolic flux. The proposed pathway for alanine entry involves the question of alanine transport into mitochondria and the possibility of the operation of an "alanine dehydrogenase" enzyme complex between mitochondrial alanine aminotransferase and glutamate dehydrogenase. When the transaminase has been successfully isolated from porcine tissues and characterized, an attempt will be made to demonstrate the formation of such a complex and to study its properties.